The overall objective of this project is to fabricate tissue-mimicking phantoms for testing state-of-the-art breast imaging equipment. Phantoms that mimic the breast, including cancerous lesions, are to be developed for use with ultrasound and nuclear magnetic resonance (NMR) instruments. Pilot work will be carried out anticipating development of phantoms for use in transmission spectroscopy imaging. A major part of this project involves the continued development of anthropomrphic breast phantoms for ultrasound imaging. This includes measuring the ultrasonic scattering properties of breast tissues and of ultrasonically tissue-mimicking materials in order to match scattering in phantoms with scattering in tissues. In addition, cooperating researchers will make comparisons via imaging between scattering properties of complete phantoms with scattering measured in vivo. Fabrication techniques will be developed to more accurately simulate the glandular region of the breast than is done in current phantoms. And a program to produce a "compressed breast" for ultrasound imaging will be completed. Finally, a program will be followed, involving cooperating clinicians, to accurately simulate different cancerous lesions in anthropomorphic phantoms. This project will also involve the development and fabrication of NMR breast phantoms. Materials closely related to those used in making ultrasound phantoms can be made to have hydrogen nucleus NMR properties spanning the range found in human tissues. Phantoms made with these materials could be used to study the effectiveness of NMR scanners in differentiating between tissues, including normal and abnormal. Fabrication of anthropomorphic phantoms of sufficient complexity for NMR applications will be facilitated by drawing upon broad experience obtained in assembling ultrasound phantoms. Studies will also be carried out to quantify the visible and infrared absorption and scattering properties of tissues and gel-phantom materials. These studies would serve as a starting point for fabrication of phantoms for transmission spectroscopy imaging. This modality also show promise as a nonionizing means of detection of breast cancer.